This application relates generally to puncture sealing fluid handling apparatus of the type which have a metallic tubular member forming a chamber for the fluid and a puncture sealing material covering the metallic tubular member. It relates particularly to fluid handling apparatus which is designed for use as fuel lines in military jet aircraft. There are numerous instances in which aircraft fuel lines might be pierced by a projectile (such as a bullet) which penetrates the aircraft fuselage. A pierced fuel line which allows its contents to continuously leak out of the puncture hole can have disastrous results.
Therefore, it has been conventional to design aircraft fuel lines with the capacity to be puncture sealing, in order to maintain the integrity of the fuel line even if it is pierced by a projectile. One very common way of constructing a puncture sealing fuel line has been to coat a metallic tubular inner member with a layer of material such as gum rubber. When the fuel line is pierced by a projectile the gum rubber tends to swell and fill the hole caused by the projectile, to thereby seal the hole against leakage of fluid.
Applicant has found that fuel lines constructed in the foregoing manner have certain disadvantages in sealing against a projectile which pierces the fuel line at one point and exits the fuel line at another point. Specifically, when a projectile exits the fuel line it tears through the metal tubing and deforms portions of the metal tubular member outwardly, a phenomenon known as petalling. The metal portions tend to penetrate deeply into the gum rubber and remain there. This means that if the layer of gum rubber is not as thick as the longest petals the gum rubber will not be able to effectively seal the puncture. This also means that in designing a fuel line to withstand penetration by a particular sized projectile the thickness of the gum rubber layer must be greater than the extent of the longest petals which are likely to be caused by such a projectile. This latter situation is believed to be particularly disadvantageous from a weight point of view.
Examples of other known forms of puncture sealing fluid conduits or containers can be found in disclosures such as U.S. Pat. Nos. 3,509,016; 3,291,333; 3,379,336; 2,429,688; 2,403,836 and 3,698,587.